The objective of this Proposal is to investigate a major health problem, tinnitus aurium. The existence of a large patient pool derived from the Tinnitus Clinic in the Department of Otolaryngology of the University of Oregon Health Sciences Center offers a unique opportunity to add significantly to the available information on tinnitus and its medical understanding of the causes, underlying mechanisms, and treatment of tinnitus. To that end, a multidisciplinary effort is proposed which will integrate a variety of investigative techniques for quantifying and evaluating the clinical manifestations of tinnitus. The resulting information will be used to develop a large computerized data base containing data relevant to tinnitus. In addition to permitting a more definitive description and classification of tinnitus than has been available previously, the research proposed below will address a number of clinically significant issues, including determination of the incidence and nature of drug-induced tinnitus; development of electrophysiological techniques as an aid in the diagnosis and evaluation of tinnitus; and evaluation of the safety and efficacy of tinnitus masking as well as drug treatments proposed for the relief of tinnitus.